High power,light weight electron tube



April 7, 1970 J. w. HAGOO D ETAL HIGHYPOWER, LIGHT WEIGHT ELECTRON TUBEFiled Sept. 15, 1957 Jerr W Ho ood Joe Shelton I M M mviszqroxs. BY fly1 United States Patent HIGH POWER, LIGHT WEIGHT ELECTRON TUBE Jerry W.Hagood and Joe Shelton, Huntsville, Ala., as-

signors to the United States of America as represented by the Secretaryof the Army Filed Sept. 15, 1967, Ser. No. 668,244 Int. Cl. H01j' 29/02US. Cl. 313-89 7 Claims ABSTRACT OF THE DISCLOSURE An electron tube isused with a high temperature radiator to provide a system of reducedweight for operation in the exo-atmosphere. A collector is adapted to bereleased and ejected partially or completely when the desired minimumaltitude has been attained. A ring similar to the accelerating anode andoperating near the same potential may be located near the collector toaccelerate an electron beam toward the radiator after the collector hasbeen discarded.

DEDICATORY CLAUSE The invention described herein may be manufactured,used, and licensed by or for the Government for governmental purposeswithout the payment to us of any royalty thereon.

BACKGROUND OF THE INVENTION It is desirable to have high power electrontubes for operation at high altitudes. One of the major problemsassociated with high power electron tubes operating at high altitudes isthe weight of the tube. This weight consists primarily of a heat sink toabsorb the heat generated by the tubes electron beam. Since electrons,when striking a collector, dissipate a significant portion of theirenergy as heat, the heat sink size and weight and that of auxiliarycooling equipment for a high power tube may be prohibitive forouter-atmospheric vehicles.

SUMMARY OF THE INVENTION The present invention is a high power, lightweight electron tube that requires no heat sink when operated ataltitudes above about 160 kilometers. The collector is one of verymodest weight, on the order of a few pounds, and the tube can befabricated using conventional techniques. The radio frequency input andoutput connections to the tube, which are normally sealed by a windowthat is transparent to microwave energy, need no longer be sealed whenexo-atmospheric altitudes are attained. The heat sinks normallyassociated with these windows are no longer necessary and unwantedstanding wave ratios magnified by sealed windows will be reduced whenthe discontinuity of the seal is removed thereby increasing the overalltube efficiency.

An object of this invention is to provide a novel highpower tube.

Another object is to provide a traveling wave tube having a disposablecollector and a heat radiator located remotely from the traveling wavetube to collect the electron beam when the disposable collector isremoved.

BRIEF DESCRIPTION OF THE DRAWING FIGURE 1 is a traveling wave tube witha voltage gradient collector having a removable end plug.

FIGURE 2 is a section of a traveling wave tube showing a constantvoltage collector in the process of being jettisoned.

FIGURE 3 is a section of a traveling wave tube showing the mating edgesof the collector shown in FIGURE 2 with the tube.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of be highpower light weight electron tube, as shown in FIGURE 1, consists of ahousing assembly 10 containing conventional traveling wave tubeelements, or other linear beam device, that requires no heat sink whenoperated at altitudes above about kilometers. The electron beam isformed in the usual manner except for a minor change in the cathode.Typically, an electron gun produces a beam of electrons which is shotthrough a long helix and collected by an electrode at anode potential.The collecter 12 consists of a series of individually insulatedcollectors maintained at separate voltage levels, with each voltagelevel (progressing in the direction of electron beam flow) lower thanthe preceding level. Therefore, the potential V is the highest collectorpotential and V is the lowest collector potential. As the electrons movethrough the decreasing potential in the segmented collector 12, the lowenergy electrons are collected near the entrance and the higher energyelectrons are collected toward the end of the collector. Since theelectrons lose energy as they move through the decreasing field, theyare collected with a minimum kinetic energy which in turn generates aminimum amount of heat at the collector. A removable end cover 14 in theend of this segmented collector depends only on the pressuredifferential for removal, and would be applicable for tubes that were tobe activated after the desired altitude is reached. The altitude atwhich the end cover is ejected depends on the degree of vacuum withinthe tube. When the tube is placed in an outer-atmosphere condition,outside pressure will decrease until the inside pressure is greater thanthe outside pressure and the cover will be forced off. This method worksequally well for the segmented collector 12 or a tube with anaccelerating ring, which will be considered later.

The gun structure is fabricated in the usual manner except that aslightly more active cathode is used to insure emission at pressures ofabout 10- millimeters of mercn'ry. These are readily available fromcommercial suppliers. A more active cathode also allows the tube toreactivate itself in the event that a leak develops while the tube is instorage. Since the environmental conditions at high altitudes act as anunlimited vacuum pump, any gas evolved during operation of the tube willbe immediately ejected without degrading tube performance. This fact maypermit the use of lighter weight materials in the tube construction,resulting in a system weight reduction.

When the inside pressure forces cover 14 from collector 12, theelectrons are allowed to exit through the open end of the tube and arecollected on a heat radiator 16 operating at a voltage V that is nearthe same potential as the collector. Radiator 16 is aligned with itsface perpendicular to and centered around the center line of the tube.

A second embodiment of the light weight electron tube, as shown inFIGURE 2, may be constructed with the collector omitted altogether orreplaced by a ring similar to the accelerating anode and operating nearthe same potential. In order to properly activate and store the tube, atemporary end is placed over the tube, and is removed after the tubereaches a predetermined altitude or pressure. After the temporary end ismoved, the tube when activated will generate an electron beam to becollected on the external heat radiator 16. An accelerating ring willserve to direct the beam over a broad area of the radiator, which willfacilitate cooling the area.

FIGURE 2 shows a method for attaching a temporary plate 20 to tube 10.This adaptation is applicable for all types of linear beam tubes. It isapplicable for tubes with a segmented collector, a plain collector, orwith only a collector ring. A removable collector may be attached inlike manner. The end plate assembly, as well as being designed for useon all types of linear beam tubes, is designed such that the tube can beactivated and tested prior to actual operation. The end plate is alwaysin electrical contact with the tube element preceding it, thus it willact as either a part of or the entire collector, depending on tubedesign.

The assembly is bolted together with the four springs 22 compressed, andis sealed by a thin foil 24 (shown in FIGURE 3) that is brazed or weldedto the end plate 20 and a collector ring 26. Explosive bolts 28 are usedto attach a metal cover plate 30 to tube 10. End plate 20' is attachedto cover plate 30 by an insulating ring 32. The explosive bolts can betriggered by a pressure switch, a timing device, or other means. Whenbolts 28 are released, springs 22 exert sufiicient force to rupture thethin foil sealing strip 24 and eject end plate 20. The electron beamwill then be directed to radiator 16.

We claim:

1. An electron tube comprising: a housing assembly; a collectorassembly; means connecting said collector to said housing, wherein saidconnecting means includes a preset release mechanism for removing atleast a section of said collector; and an external heat radiatorco-axially aligned with and adjacent to said collector assembly toattract electron flow when said collector section is removed.

2. The electron tube is set forth in claim 1 wherein the collectorassembly includes a segmented collector composed of a series ofcollectors insulated from each other and maintained at separateincremental voltage levels.

3. The electron tube as set forth in claim 2 wherein said segmentedcollectorhas a removable end plate held in place by pressure external tothe tube.

4. The electron tube as set forth in claim 1 wherein said collectorassembly includes a collector ring permanently attached to but insulatedfrom said housing assembly and a removable end plate covering saidcollector ring.

5. The electron tube as set forth in claim 4 wherein said connectingmeans is attached to the removable end plate and wherein said connectingmeans includes a cover plate with attached explosive bolts for removingsaid coverplate from the tube.

6. The electron tube as set forth in claim 4 wherein a thin metal foilforms a seal between said collector ring and said removable end plate.

7. The electron tube as set forth in claim 6 wherein said connectingmeans is attached to the end plate, and includes a coverplate attachedto said housing assembly so as to be easily detached.

References Cited UNITED STATES PATENTS 3,175,120 3/1968 Wendt 3155.383,368,104 2/1968 McCullough 3155.38 3,414,757 12/1968 Levin ct al.315-538 HERMAN KARL SAALBACH, Primary Examiner S. CHATMON, JR.,Assistant Examiner US. Cl. X.R.

